基于透明土和三维重构技术的空间变形可视化测量系统的研究

Study of visualization measurement system of spatial deformation based on transparent soil and three-dimensional reconstruction technology

常规的可视化模型试验中,能够观察到二维观测视窗中的位移变形,但是却无法获取三维问题的离面位移以及三维空间变形场。为此,基于透明土模型试验,自主开发了一套自动层析扫描测试装置,通过高精度电动线性平台控制着相机和激光器同步运动,获取一系列二维图片。利用改进的图像变形测量方法进行图像后处理。在此基础上,自主编写了相应的三维重构的体绘制程序,用于构建变形后的三维位移场。为了验证空间变形可视化测量系统的可行性,开展了方形基础和圆形基础透明土静压试验。试验结果表明:重构后的三维竖向位移和水平位移等值面云图的变化规律和理论预测结果以及前人文献中所提到的规律一致,三维矢量位移场可以直观地显示不同位置的土体运动规律,能弥补二维观测技术不能反映离面位移的局限性。该研究不仅可以进一步地揭示静压试验中的三维空间变形问题,同时还证明该方法对于实现物理模型试验中观测三维空间变形问题是可行的。

In the conventional visualization model test,the displacement and deformation in the two-dimensional observation window can be observed,but the out-of-plane displacement of the three-dimensional(3D)problem and the 3D deformation field cannot be obtained.Therefore,based on the transparent soil model test,a set of automatic tomographic scanning test device is independently developed in this study.The synchronous motion of the camera with the laser device is controlled by a high-precision electric linear platform to obtain a series of two-dimensional images.The improved image deformation measurement method is used for image post-processing.On this basis,the corresponding 3D reconstruction volume rendering program is coded to construct the 3D displacement field after deformation.In order to verify the feasibility of the visualization measurement system of spatial deformation,static pressure tests of square foundation and circular foundation in transparent soil are carried out.The test results show that the contour of the 3D vertical displacement and horizontal displacement after reconstruction are consistent with the theoretical prediction results and with those previously presented in the literature.The 3D vector displacement field can directly show the movement of soil mass at different positions,which eliminate that the 2 D observation technique cannot reflect the out-of-plane displacement.This study not only further reveals the spatial deformation problem in static pressure test,but also provides a feasible method for realizing the observation of spatial deformation in the physical model test.